As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING LANDING SET-UP WHEN LANDING GEAR HANDLE PUT IN DOWN POSITION, NONE OF THE LANDING GEAR EXTENDED AND HAD 3 RED UNSAFE LIGHTS. CREW USED ALTERNATE EXTENSION. AIRCRAFT LANDED WITHOUT INCIDENT. CURRENTLY TROUBLESHOOTING PROBLEM 7/24. MX REPLACED THE SELECTOR VALVE AND GEAR HANDLE.